The present invention relates, in general, to an automatic container locking apparatus for trailers and, more particularly, to an automatic container locking apparatus, installed in the deck of a trailer and automatically operable in response to the weight of a container to lock or unlock the container on the deck of the trailer, thus securely and safely holding the container on the deck while transporting the container on a road, and being convenient to workers while loading or unloading the container onto or from the deck of the trailer.
As well known to those skilled in the art, a container is a large, vanlike, reusable box for consolidating smaller crates or cartons into a single shipment, designed for easy and fast loading and unloading of freight. Such a container is loaded on a trailer, and is transported by a truck tractor on a road In order to hold such a container on the deck of a trailer while transporting the container on a road, a plurality of locking apparatuses are installed in the deck at predetermined positions. Such an installation of the locking apparatuses on the deck of a trailer is prescribed by law.
FIGS. 1a and 1b are sectional views, showing an operation of a conventional container locking apparatus for trailers when the locking apparatus locks a container in position on the deck of a trailer. As shown in the drawings, the conventional container locking apparatus, installed in the deck 1 of a trailer at a predetermined position, comprises a locking bolt 2. This locking bolt 2 is vertically movable and rotatable by an actuation of a lever 3, thus locking or unlocking a container 4 on the deck 1. In order to lock the container 4 to the deck 1, the container 4 is primarily seated on the deck 1 at a predetermined position. Thereafter, the lever 3 of the locking bolt 2 is manipulated by a worker to fully insert the top head 2xe2x80x2 of the locking bolt 2 into a locking hole 5 formed on the bottom of the deck 1, thus locking the container 4 in position on the deck 1.
Therefore, the locking apparatus holds the container 4 on the deck 1 of the trailer while transporting the container on a road, and prevents the container 4 from being undesirably moved on the deck 1 or unexpectedly dropped from the deck 1 onto the road during such transportation.
However, such conventional container locking apparatuses for trailers are somewhat difficult to manipulate, and so some workers or drivers of truck tractors often neglect to lock the containers in position on the decks of trailers. When a container is transported on a road while being not locked to the deck of a trailer as described above, the container may be undesirably moved on the deck or unexpectedly dropped from the deck onto the road. Particularly when the truck tractor, with the trailer seating a container thereon without being locked to the deck of the trailer, turns a corner or encounters an uneven surface of a road, the container may be more easily removed from the deck 1 to cause severe traffic accidents.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an automatic container locking apparatus for trailers, which is installed in the deck of a trailer, and is automatically operable in response to the weight of a container to lock or unlock the container on the deck when it is desired to load or unload the container onto or from the deck.
In order to accomplish the above object, the present invention provides an automatic container locking apparatus for trailers, comprising a housing vertically set in the deck of a trailer at a predetermined position, an actuator having a hollow structure with a central opening, the actuator being axially and movably set within the housing while being normally biased upward by a first compression coil spring such that the actuator is vertically extendible and retractable relative to the upper end of the housing, a longitudinal locking bolt having a head at its upper end and movably and concentrically set within the central opening of the actuator such that the locking bolt is removably inserted into a locking hole of a container at the head, with a stopper externally formed on the sidewall of the locking bolt at a predetermined position to selectively come into contact with the lower surface of the actuator, thus allowing the locking bolt to be selectively and vertically movable in conjunction with a vertical movement of the actuator, a hole longitudinally formed at the center of the locking bolt while extending from the lower end of the locking bolt to a predetermined depth, with a curved guide slit formed on the sidewall of the locking bolt to communicate with the hole, a support shaft vertically standing within the housing while being fixed to the bottom lid of the housing at its lower end, the support shaft being axially, upwardly and movably inserted into the hole of the locking bolt from the lower end of the locking bolt, with a second spring set within the hole of the locking bolt to normally bias the locking bolt upward, and an actuation pin formed on the sidewall of the support shaft at an upper portion, and movably engaging with the curved guide slit of the locking bolt, thus allowing the locking bolt to be rotatable relative to the actuator at a predetermined angle when the locking bolt is vertically moved in response to external pressure applied from the container downward to the actuator.